What is it? Why is it used?
A PET/CT scan is an effective way of revealing or evaluating several conditions, including many cancers, heart disease and brain disorders. It often detects disease before it shows up on other imaging tests or when standard tests are inconclusive. This type of information can be life-changing and helps physicians improve treatment planning for their patients.
A PET/CT scan uses a radioactive drug (tracer) to identify areas of your body that have higher levels of chemical activity, which often correspond to areas of disease. On a PET/CT scan, these areas show up as bright spots. PET detects changes in cellular metabolism (how active a cell is), often indicating the presence of disease. CT detects changes in the physical size or shape of a lesion and shows exactly where in the body the lesion is located.
Cancer cells show up as bright spots on PET scans because they have a higher metabolic rate than do normal cells. PET scans may be useful in:
- Detecting cancer
- Revealing whether your cancer has spread
- Checking whether a cancer treatment is working
- Finding a cancer recurrence
- PET scans must be interpreted carefully because noncancerous conditions can look like cancer, and some cancers do not appear on PET scans. Many types of solid tumors do appear on PET scans, including:
- Head and neck
- Prostate Cancer
PET measures the metabolic and functional activity of the heart, the presence and distribution of damaged or dead heart muscle, and the selection and monitoring of appropriate interventions, including cardiac surgery. PET/CT scans are uniquely suited to detect infections or inflammation in the heart muscle, valves, or blood vessels, including infections or replacement valves or of implanted device such as pacemakers. PET/CT in cardiology is used in the following areas:
- May be suspected in non-ischemic heart failure
- Diagnosis when MRI equivocal
- Detection of extracardiac manifestations
- Monitoring response to therapy
Infectious and Inflammatory conditions including:
- Implanted devices infection
- Vascular graft infection
- Suspected inflammatory/infectious myocarditis
PET/CT scans can be used to evaluate certain brain disorders, such as:
- Differential, early (before change on MRI) diagnosis of dementia:
- Mild cognitive impairment): AD vs non-AD
- Alzheimer’s Disease
- Vascular dementia
- Frontotemporal dementia
- Dementia with Lewy bodies
- Excellent prognostic value in a negative test
Study: PET/CT of Dementia
Traumatic Brain Injury
Demonstration of abnormal metabolic findings even with normal MRI anatomy
- Metabolic abnormalities correlate with mechanism of injury
- Findings correlate with abnormalities demonstrated on neuropsychological testing
- Interictal FDG PET has high sensitivity for extra-temporal epilepsy
- Detection of temporal lobe epilepsy despite normal MRI
- “MRI-negative PET-positive” temporal lobe epilepsy
By the Numbers
A recent Canadian study by Worsley et al. (2010) found that the information derived from PET imaging resulted in a change in intended treatment plans in 50% of cases (1).
PET imaging allows physicians to avoid costly biopsy surgeries in as many as 70% of cases (1).
Role Within Health Care Systems
What is the risk?
- It is similar in terms of safety to diagnostic procedures found in radiology (e.g. X-rays, MRIs)
- Millions of PET scans have been performed worldwide.
- The exposure level to radiation is very small and is considered safe for a medically-appropriate diagnostic procedure.
- The radioactive tracers used in PET/CT disappear from your body completely within 24 hours.
- We employ all safety measures and safety equipment and are happy to provide more information about any of our procedures.